The current microbiology/infectious disease literature states that prognosis and therapy of cryptococcal meningitis are directly related to the titers of cryptococcal antigen found in the cerebrospinal fluid and that at the end of therapy, the cryptococcal antigen titer should be approaching zero. The aforementioned is based upon data derived at NIH using a commercially unavailable research assay for the determination of cryptococcal antigen titers. Recent personal communications from outside institutions of titers in treated patients exceeding 1:4000 and as high as 1:41,000 using commercial antigen kits have created concern among clinical pathologists and infectious disease clinicians. In a number of cases prolonged antifungal therapeutic courses have been administered because of the persistent high titers. We will determine cerebrospinal fluid cryptococcal antigen titers using three commercially available kits. We hope to be able to establish correlations between cryptococcal antigen titers and the clinical and microbiological status of the patient.